How are cliffs erode?

cliffs erode because when the ocean waves hit the rock they bring back pebbles and sediment. this eventually erodes and "eats" at the rock. this forms a cliff.

Yes wind does erode the clifflittle by little.

"The cliffs (of Dover on the Brittish Coast) themselves are still under attack from the sea as its continuous flow eats away at the soft chalk at the base of the cliffs. About 2-5cm on average are...

it can take from around 5 minutes to millions and millions of years

cliff erosion begins at the base, erodes a notch from the bottom and removes fallen debris. this produces instability and results on constant recession.